Several technologies including Orthogonal Frequency Division Multiplexing (OFDM), Multiple Input Multiple Output (MIMO), a smart antenna, and the like have been introduced to accomplish high data rates. However, where a high frequency band is used, a shadow area in downtown areas is expected to increase.
Research on a relay station is being actively pursued to solve a problem caused by the shadow area and to improve a data rate. Recent technologies related to the relay station include an amplify-and-forward scheme of power, a decode-and-forward scheme, a reconfiguration/reallocation-and-forward scheme, and the like.
Where a relay station is included in a communication system, a wireless resource such as a time slot for the relay station is typically needed. For example, it is assumed that the relay station operates between a base station and a mobile station. The base station transmits a message A to the relay station during a time slot T1, T1 being one of downlink time slots, and the mobile station transmits a message B to the relay station during a time slot T2, T2 being one of uplink time slots. In this case, the relay station transmits the message A to the mobile station during a time slot T3, T3 being one of the downlink time slots, and transmits the message B to the base station during time a slot T4, T4 being one of the uplink time slots.
In the example above, a minimum of four time slots T1, T2, T3, and T4 are needed to exchange the message A and message B between the base station and the mobile station via the relay station.
Where the base station and the mobile station directly transceive the message A and message B without passing through the relay station, only two time slots may be needed. That is, where a relay station is added to a communication system, a wireless resource such as a time slot and the like is additionally consumed.
Accordingly, a technology for maximizing a data rate by reducing consumption of a wireless resource, such as, for example, where a relay station requiring a time slot is added to a communication system, is needed.